Department of Materials Science and Engineering, Massachusetts Institute of Technology, Boston, MA, United States.
Osteoarthritis Cartilage. 2011 Oct;19(10):1199-209. doi: 10.1016/j.joca.2011.07.013. Epub 2011 Jul 29.
Fetal cartilage anlage provides a framework for endochondral ossification and organization into articular cartilage. We previously reported differences between mechanical properties of talar cartilage anlagen and adult articular cartilage. However, the underlying development-associated changes remain to be established. Delineation of the normal evolvement of mechanical properties and its associated compositional basis provides insight into the natural mechanisms of cartilage maturation. Our goal was to address this issue.
Human fetal cartilage anlagen were harvested from the tali of normal stillborn fetuses from 20 to 36 weeks of gestational age. Data obtained from stress relaxation experiments conducted under confined and unconfined compression configurations were processed to derive the compressive mechanical properties. The compressive mechanical properties were extracted from a linear fit to the equilibrium response in unconfined compression, and by using the nonlinear biphasic theory to fit to the experimental data from the confined compression experiment, both in stress-relaxation. The molecular composition was obtained using Fourier transform infrared (FTIR), and spatial maps of tissue contents per dry weight were created using FTIR imaging. Correlative and regression analyses were performed to identify relationships between the mechanical properties and age, compositional properties and age, and mechanical vs compositional parameters.
All of the compositional quantities and the mechanical properties excluding the Poisson's ratio changed with maturation. Stiffness increased by a factor of ∼2.5 and permeability decreased by 20% over the period studied. Collagen content and degree of collagen integrity increased with age by ∼3-fold, while the proteoglycan content decreased by 18%. Significant relations were found between the mechanical and compositional properties.
The mechanics of fetal talar cartilage is related to its composition, where the collagen and proteoglycan network play a prominent role. An understanding of the mechanisms of early cartilage maturation could provide a framework to guide tissue-engineering strategies.
胎儿软骨原基为软骨内骨化和关节软骨形成提供了一个框架。我们之前报道了距骨软骨原基与成人关节软骨之间机械性能的差异。然而，其潜在的发育相关变化仍有待确定。阐明机械性能的正常演变及其相关的组成基础，可以深入了解软骨成熟的自然机制。我们的目标是解决这个问题。
从 20 至 36 孕周正常死产胎儿的距骨中采集人胎儿软骨原基。在约束和非约束压缩配置下进行的应力松弛实验获得的数据被处理以得出压缩力学性能。通过在非约束压缩中的平衡响应的线性拟合来提取压缩力学性能，并且通过使用非线性双相理论拟合约束压缩实验的实验数据，在应力松弛中都可以得到压缩力学性能。使用傅里叶变换红外光谱（FTIR）获得分子组成，并且使用 FTIR 成像创建组织含量的空间图谱。进行了相关和回归分析，以确定机械性能与年龄、组成特性与年龄以及机械与组成参数之间的关系。
除泊松比外，所有组成量和力学性能都随着成熟而变化。在研究期间，刚度增加了约 2.5 倍，渗透率降低了 20%。胶原含量和胶原完整性程度随年龄增加了约 3 倍，而蛋白聚糖含量减少了 18%。在力学和组成特性之间发现了显著的关系。
距骨软骨胎儿的力学性能与其组成有关，其中胶原和蛋白聚糖网络起着重要作用。对早期软骨成熟机制的理解可以为指导组织工程策略提供框架。
